Mobile voice communications technology has enjoyed substantial growth over the past decade. Many cars, trucks, airplanes, boats, and other vehicles are equipped with devices that allow convenient and reliable mobile voice communications using a network of satellite-based or land-based transceivers. Advances in this technology have led to widespread use of mobile units, such as hand-held or vehicle-mounted cellular telephones, for voice communications.
Many users of mobile units desire continuous and reliable service as they travel across long distances. For example, a cellular telephone in a vehicle or carried by a person may travel through many different cellular systems offering a range of subscriber features. Calls placed to these roaming phones must be routed to the current communications service provider. Traditional roaming technology delivers calls placed to these roaming phones using the communications infrastructure of the cellular telephone network. Typically, the roaming phone registers with a communications service provider and notifies the home communications service provider of the registration.
The roaming services provided through the cellular telephone infrastructure introduce additional complexity and communications traffic in the system and come at a substantial cost to the end user. The communications service providers utilize additional equipment and communications bandwidth to register roamers and report the registration to the home switch of the roaming phone. Users are charged a premium for these services.